Well, it can depend on what origin/destination you're working with. Hub to hub, (say SFO-ORD) can be overloaded with GS and 1K's. If you're not one of them, even if you have a paid F ticket, you may be in the way-back of group 1. At ORD, for a late afternoon flight to SFO on a Friday, that leverage may be worth squat for where your luggage can be, even if you showed up with what you thougt was time to spare.

Ten years ago, I was flying the ORD-SFO leg in a late afternoon flight on a Thursday. The line for the GS/1K pre-boards had over 55 pax. I counted them. I was in the tail end of the group 1 line. For whatever reason, my attempt for my bag to be near me in seat 4F was zilch. The FA in F made little attempt to help me, and after being pressured by her GA, insisted that I check may bag. I protested, politely, then more insistently. They checked my bag, and then it never appeared at landing at SFO. They couldn't find it for 2 days. I had over 2mm miles on UA at the time and some important academic papers for what I had been working on.

Needless to day, I was po"d and flew other carriers, mostly AA and DL. My policy of never checking bags was derailed by UA. I think I've only had 3 flights on them in the last 10 yrs, mainly because I couldn't get around avoiding them. I suppose I would have made lifetime 1K if I had stuck with UA, but .... Don't have much regret. Always walk with my fleet when I have been diss'd by an airline. So having an F ticket and showing up in a reasonable time at hub-hub routes is not a guarantee of happiness. And no, I could have spent enough to make 1K on some of those years to get to be a pre-board, but my capacity for forgiveness to UA went to zilch. I don't regret flying other carriers on the west coast, especially AS, HA, and AA. Funny thing, AS lets me board as a pre-board anytime I ask, no questions asked. Wished UA had done that. I''m approaching 1MM on AS and have already made lifetime EXP, as well as lifetime DL Gold medallion. Hope Kirby missed my $$.